Lancets

ABSTRACT

A return spring arrangement for a lancet ( 6 ) is provided by a pair of undulating plastic webs ( 14 ) formed integrally with the lancet. The undulations of the two webs ( 14 ) are shown out of phase with one another. These webs ( 14 ) are flexible and thus are caused to concertina when the tips ( 15 ) of the webs hit the interior of a lancet holder on release of a drive spring. The energy stored within the collapsed webs ( 14 ) is then released to drive the lancet back within the lancet holder. This positive return of the lancet ensures that a needle ( 5 ) will retract safely into the lancet holder, after operation, and does not rely on the spring being locked into the lancet holder and onto the lancet.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a division of application Ser. No. 10/567,554 (nowU.S. Pat. No. 7,713,280) filed on Mar. 15, 2006, which is the 35 U.S.C.§371 national stage of International PCT/GB04/03676 filed on Aug. 27,2004, which claims priority to British Application No. 0320283.5 filedon Aug. 29, 2003. The entire contents of each of the above-identifiedapplications are hereby incorporated by reference. Any disclaimer thatmay have occurred during prosecution of the above referencedapplications is hereby expressly disclaimed.

BACKGROUND OF THE INVENTION

Lancet devices are used for taking blood samples by projecting a needlerapidly and momentarily out of the casing so as to prick the skin of apatient. The device needs to have some means of causing the needle to bereturned into the casing after it has served its purpose and there isusually a drive spring which, when released, drives the needle forwards,overshooting its static position. It then returns to this position todrive the needle back in the casing. It is an object of this inventionto provide spring return means for the lancet which is relatively cheapto manufacture and simple to install, and which removes the need forlocating the return spring at the casing and lancet.

SUMMARY OF THE INVENTION

According to the invention there is provided a lancet comprising a bodyhaving a drive head at one end and a projecting needle at the other end,the body having integral webs projecting down both sides towards thelocation of the tip of the projecting needle, the webs being ofundulating form and of a flexible material so as to act as springmembers.

By utilising undulating webs as spring members, the webs can be mouldedat the same time as the body of the lancet, thus saving on bothmanufacturing and assembly time as there is no separate return springdevice which needs to be attached.

The undulations of the two webs may be out of phase with one another.

The lancet is ideally provided with a removable protective cap which issituated over the exposed end of the needle. The cap could be linked tothe free ends of the webs by breakable connecting parts.

The invention also extends to a lancet holder comprising a casinghousing a lancet of this invention as hereinbefore defined, and having adrive spring positioned between an end of the housing and the drive headof the lancet.

A release structure for the lancet can be provided in the form of thedrive head of the lancet incorporating a flange resting against amoveable rib of the casing, together with a flexible button on thecasing which is movable to release the rib from the flange to enable thedrive spring to drive the lancet forwards.

The needle tip can be covered by a removable protective cap providedwith a head which locates over flanges on the casing, but can be twistedout of contact with the flanges to enable the cap to be removed toexpose the tip of the needle.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention may be performed in various ways and a preferred examplethereof will now be described, with reference to the accompanyingdiagrammatic drawings, in which:

FIG. 1 is a perspective view of a lancet holder of this invention;

FIG. 2 illustrates the lancet holder of FIG. 1 in an opened condition;and

FIG. 3 is an illustration of a lancet as is enclosed within the holderof FIGS. 1 and 2.

DETAILED DESCRIPTION OF THE INVENTION

The lancet holder shown in FIG. 1 comprises an outer casing 1 from whichprojects an operating button 2. At the other end, the head 3 of aprotective cap projects. As can be seen from FIG. 2, the cap has anextending shaft 4 which covers and protects the tip of a needle 5 of alancet 6 (see FIG. 3). The head 3 of the cap can be twisted to releaseit from engagement with flanges 7 at the end of the casing 1, enablingthe cap to be pulled free of the needle 5 on the end of the lancet 6,when the device is to be used.

The lancet 6 is primed by a spring 8, but is held within the casing 1 bya rib 9 forming part of the casing 1 resting against a flange 10 on thelancet 6. In use, webs 11 on the operating button 2 will move furtherinwardly of the casing 1 when the button 2 is pressed, and will move therib 9 (which is resiliently attached to the casing 1) away from theflange 10, thus releasing the lancet 6. The lancet is now drivenforwardly by the coil spring 8 to cause the needle 5 to project throughan opening 12 in the end of the casing 1. With the casing 1 held againstthe skin of a patient (prior to operation of the button 2), the needlewill then penetrate the skin to enable a small blood sample to be taken.

As is usual with such lancets the needle only projects momentarily andthen is withdrawn automatically into the housing 1. This is usuallypartly by a bounce-back of the spring 8. However, for this device aspring arrangement 13 positively pushes the lancet back into the casing.This spring arrangement is created by a pair of undulating plastic webs14 formed integrally with the lancet 6. These webs 14 are flexible andthus are caused to concertina when the tips 15 of the webs hit theinterior of the flange members 7. The energy stored within the collapsedwebs 14 is then released to drive the lancet back within the casing 1.As can be seen from FIG. 3, the undulations of the two webs 14 may beout of phase with one another. This positive return of the lancetensures that the needle will retract safely into the casing, and doesnot rely on the spring being locked into the casing and onto the lancet.

During manufacture the lancet body 6 is moulded about the needle 5 andthe webs 14 are moulded integrally with the body 6. The tips 15 of thewebs 14 can additionally be linked, during the moulding process, by thinconnecting parts to the shaft 4 of the cap for the needle. This holdsthe cap against being twisted accidentally. However, when a deliberatetwisting motion is created on the head 3 of the cap, the thin connectingparts linked to the webs 14 fracture, thus allowing the cap to beremoved. As can be seen particularly from FIG. 2, guide ribs 16 areformed within both halves of the casing 1 to guide the lancet whilst itis being driven by the spring 8. The two halves of the casing 1 areintegrally moulded to incorporate flexible hinges 17. When the lancet 6and cap 3, together with the spring 8, have been loaded into one half ofthe casing, the two halves of the casing can be folded together so thatstuds 18 enter tight fitting holes 19 to grip the two halves of thecasing together.

What is claimed is:
 1. A lancet holder including a casing housing a lancet, the lancet comprising: a body having a drive head at one end and a projecting needle at an other end, the body having two webs molded integrally with said body and projecting along respective sides of said body towards a tip of the projecting needle, each of the webs having one end merging with the body and another end spaced from the body and each of the webs being of undulating form when in a relaxed condition and of a flexible material so as to act as spring members to return the lancet to a retracted position; the lancet holder having a drive spring positioned between an end of the casing and the drive head of the lancet.
 2. The lancet holder according to claim 1, wherein the undulations of the two webs are out of phase with one another.
 3. The lancet holder according to claim 2, wherein a removable protective cap is provided over an exposed end of the needle.
 4. The lancet holder according to claim 1, wherein a removable protective cap is provided over an exposed end of the needle.
 5. The lancet holder according to claim 4, wherein the cap is linked to free ends of the two webs by breakable connecting parts.
 6. The lancet holder according to claim 1, wherein the drive head of the lancet incorporates a flange resting against a movable rib of the casing and a flexible button on the casing is moveable to release the rib from the flange to enable the drive spring to drive the lancet forwards.
 7. The lancet holder according to claim 6, wherein the needle tip is covered by a removable protective cap provided with a head which locates over flanges on the casing, but can be twisted out of contact with the flanges to enable the cap to be removed to expose the tip of the needle.
 8. The lancet holder according to claim 1, wherein the needle tip is covered by a removable protective cap provided with a head which locates over flanges on the casing, but can be twisted out of contact with the flanges to enable the cap to be removed to expose the tip of the needle.
 9. The lancet holder according to claim 1, wherein said body includes a substantially planar portion adjacent to said one end having the drive head, a plane passing through each undulation of a respective one of said webs being perpendicular to said planar portion. 